CAD files for knife blanks

Nathan the Machinist said:
Sure, not at all. Mine was just a cautionary tale. If you're doing it right, you're doing it right.

Re: your "challenge"

Here is an easy one. It is easy to do well, it would also be easy to do badly.

1a.jpg


Trace that and I'll give you my opinion of your efforts. :thumbup:



Though I'll point out, my concern is more about creating in the computer in the first place. For a lot of folks, is it an awkward canvas to create in , and it frequently shows...
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Nathan,
I just logged in and found your post. I'll have you a DWG file in a few minutes.
 
Nathan the Machinist said:
Sure, not at all. Mine was just a cautionary tale. If you're doing it right, you're doing it right.

Re: your "challenge"

Here is an easy one. It is easy to do well, it would also be easy to do badly.

1a.jpg


Trace that and I'll give you my opinion of your efforts. :thumbup:



Though I'll point out, my concern is more about creating in the computer in the first place. For a lot of folks, is it an awkward canvas to create in , and it frequently shows...
Click to expand...

Nathan,
Forgive my lack of experience here in the forum. I can't seem to attach the file. Anyone want to point me in the right direction? Thanks.
 
Well, bummer. I apparently can't post a file. I read the FAQ and it shows how, but when I followed the instructions given there still is no option to do it. Anyone interested in getting the file (DXF or DWG) by email shoot me an email and i'll send you the files. This works and is faster than I can do it any other way. It took less than me 15 minutes to do the TRACE and convert to both DXF & DWG files. Actual time was about 3 minutes!
 
clw3 said:
I usually sketch things on paper first then scan it. I then use Adobe Illustrator to layout how the whole thing looks and then I copy my illustration and remove all but the outlines to get my template. I can take the outline and save as DXF if I want to send it out for waterjet, but so far I have only done them by hand. I just print them on a heavy paper and stick them down to my steel.

TIP: One trick I have been using to make the paper patterns more durable is to spray them with clear spray paint until the paper is soaked through and let it dry, then apply it to the steel. The paint helps the paper resist coming apart when it gets wet with water or cutting fluid.

I make my outlines black except for the areas where I'm going to drill. The dot on my optical punch is black so I use blue on the drawing where there are crosshairs so I can easily see where to line it up.

Rendering it in Illustrator allows me to experiment with different handle variations and curves to tweak the design visually before prototyping it.

Here's an example.
small-hunterII-v3.jpg
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CLW3,
Excellent ideas! :thumbup: I truly envy you folks who can generate drawings like the one you posted. Gorgeous knife!! I did a trace of it and if you are interested in seeing how close my method converts over into your CAD program shoot me an email & I'll send it to you. Took about three minutes to do.
 
I have your file. It came in with no problems.

This image is a profile of the trace juxtaposed with the original.

trace.jpg
 
The bottom image seems to be a more fluid profile. The top image is more angular and doesn't flow as nicely around the belly of the blade and the spine around the tip isn't as clean a curve as the bottom image. There's a slight difference in the guard areas as well.

Knowing what little I know about autotrace programs, I wager the bottom image is the original.

It's pretty close though. I think it would be a way to get close to what you want and then tweak the vectors to get a final draft.
 
clw3 said:
The bottom image seems to be a more fluid profile. The top image is more angular and doesn't flow as nicely around the belly of the blade and the spine around the tip isn't as clean a curve as the bottom image. There's a slight difference in the guard areas as well.

Knowing what little I know about autotrace programs, I wager the bottom image is the original.

It's pretty close though. I think it would be a way to get close to what you want and then tweak the vectors to get a final draft.
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You are correct. I'm especially impressed you saw the difference in the choil.

At no point was I debating Larry's ability to trace something (though to my eye, the trace is not quite there yet, though that could be a translation error in his export settings), my point was this: People need to be very careful how they incorporate CAD in their knife build process because creating in CAD can be a cumbersome and unnatural environment and frequently leads to awkward designs because the CAD tool drives the design.
 
Good eye indeed, clw3.

Good thread too.

In EZ Cad's defense, I think the profile discrepancies are insignificant if we assume that the blank would be cut via WJ. (Because a WJ blank needs a little clean-up).

On the other hand, Nathan machines his blanks, so his application is a bit more demanding.


EZ Cad - I opened your dxf files (thanks for the email), and they did seem clean and problem-free for the circa-1995 Flow waterjet software that I use. 3 minutes is certainly fast.
 
Nathan/clw3/Patrick,
I am thrilled that they came out as close as they did! I had no way to verify it except how Nathan suggested (short of actually cutting them out). Thanks for the input! As to the EXPORTing causing the discrepancies I doubt that. Please keep in mind ... I really whipped those out. What I EXPORTed WAS IN FACT what I drew up. A person could do a much more "fluid" file by taking a little extra time and ZOOMing in on the nodes to verify how they "flow" prior to EXPORTing. I'm really excited to know that this process will work to be able to generate files that can be cut out as multiple blanks. Thanks again for your input. :thumbup::thumbup::thumbup:
 
I do all my designs in CAD first. Ok...yes, I have done a few by drawing first...and even some by just freehand grinding some barstock. But 95% of my stuff was first drawn out in CAD.

That said, I've been doing CAD since 1994...so, I'm not a newbie...and it comes naturally to me.


Also....while I do try to make good CAD files to send to be waterjet cut...I do anticipate reprofiling them (cleaning 'em up) and 'feathering' the profile to get those nice arcs, or straight lines, etc. IOW, I don't let the machine do it and leave it there. The waterjet cutter does what it does great...but I bring what I have to the table too.


Has anybody used SketchUp to design knives? I've started using it for woodworking projects...very intuitive once you're used to it...and much less labor-intensive than most industry-standard CAD programs.


I say go for it....do your best to avoid the "over-CADing" that Nathan mentions and have some fun with it.

Dan
 
Daniel Koster said:
.


Has anybody used SketchUp to design knives? I've started using it for woodworking projects...very intuitive once you're used to it...and much less labor-intensive than most industry-standard CAD programs.

Dan
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Dan,
I you are referring to GOOGLE SketchUp, it is awesome. I have played with it, but not extensively. Unfortunately, I have to always pick which of my passions will get my attention at any given time. Trying to "perfect" a way to draw up various knife profiles in 2D via various CAD programs seems to have been winning out for quite a while now. :D Trust me when I say that I have MANY files drawn up!
 
I use SolidWorks and old 2D AutoCad every day (I can't let go of 2d autocad. Old habits die hard). I've designed knives on them, and will most definitely use software if I ever get the gumption to make folding knives.

However, one of the things I've found most exciting about making knives is the artistic, free flowing knife that develops as I profile it. I start with a template to make the initial profile, then it just ends up at what it is when I profile it on the grinder. I had no idea I would enjoy that aspect as much as I do. To each his own.....
 
Hey guys. I'm new in here, but thought I'd jump in. I use a waterjet and cnc for stone countertops, and do all my work in autocad for programming. I can vouch for ez-cad. It's not hard to take a picture, import it into cad, and redraw it for use in the waterjet. I do have to say, I think he's going about it a long way, but if that works for him, great! I have had success in copy/pasting jpg and other picture files into autocad and tracing them, then scaling to whatever size I want. These line drawings then import really nice into the waterjet program. I'm actually going to cut one for myself a little later today while I'm on break (I'm at work now).

As for the knives designed in cad looking like they're designed in cad, I don't know about that. I suppose it's all in the person running the program. (not to speak ill of anyone in here -- I don't even know ya'll) I just know that, in my experience, if you take a little time and fillet your radiusses and make everything look really smooth, they'll come out really smooth. I wish I had some pics to show ya'll, but I don't (like I said, I'm at work right now). I'll be watching this thread though. I wanna see what others have to say/show.

Joe
 
It's not so much about smoothness as it is about being overly geometric, instead of fluid (think compass instead of french curve.) You can have it be perfectly smooth by having a bunch of arcs tangent to their neighbors, but it can still be noticeably inorganic looking.
 
Beaglebow said:
I can vouch for ez-cad. It's not hard to take a picture, import it into cad, and redraw it for use in the waterjet. I do have to say, I think he's going about it a long way, but if that works for him, great! I have had success in copy/pasting jpg and other picture files into autocad and tracing them, then scaling to whatever size I want.

Joe
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Joe,
Talk about a ton of bricks! I NEVER even considered importing the picture file into the CAD program to do the trace. I gotta try that tonight. Thanks for your input, Sir!
 
Lucky Bob said:
It's not so much about smoothness as it is about being overly geometric, instead of fluid (think compass instead of french curve.) You can have it be perfectly smooth by having a bunch of arcs tangent to their neighbors, but it can still be noticeably inorganic looking.
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Yup. pretty much.

For example, there are differently levels of continuity. C0 (or G0), which means that two curves are connected (no gap), C1 (or G1) meaning two curves are connected and are tangent, and C2 (or G2) meaning true curvature continuity. Don't confuse the "G0, G1 and G2" with machine G codes. It is just the nomenclature that Parametric Technology Corporation uses vs others.

What this means... As an example - if you made a blade and had an edge profile that was one radius, and a belly that was another radius, and the two radii are tangent you have G1 continuity. The curvature would be a constant radius, meaning the rate of curvature would be constant, then at the point of tangency the rate of curvature would suddenly change to a different radius with a different constant rate of curvature. It is a sudden and instantaneous change in the rate of curvature at the tangent point. It is not a slick and natural shape. G2 continuity is a gradual and smooth change in the rate a curvature rather than a discrete tangent point between two radii. So there is no point where your eye catches and says that is the point where the radius of this line changes.

G2 curvature can not be achieved with lines and arcs.

There is much more to smooth and organic lines than this (and that is just one element to a design), but this is a fundamental.

Look at this knife by a prominent maker.

3143360125_3829060693_b.jpg


One thing I like about this maker is the sophistication of his form. He has a master's degree in fine art, and I think his understanding of form and design show in his knives. And the curves in his designs are sublime and extremely well executed. And most CAD is not intended to create shapes like this.
 
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